Despite everyone calling him a fascist, Donald Trump may have more in common with Jefferson Davis than he does with Benito Mussolini.

"What we're seeing [with Trump's rise] is what I would call the second Civil War," Steve Ross, a history professor at the University of Southern California, told The Huffington Post.

It's not that all of Trump's supporters want to own slaves or secede from the United States. But they can see their political clout disappearing, and are responding by supporting an extremist movement.

"In 1860, Abraham Lincoln wins the presidential election and for the first time in American history a president can get elected without getting a single electoral vote from the South," Ross said.

Southerners could see the writing on the wall: a future in which the North could keep electing presidents without them, and eventually outlaw slavery -- either through Congress or the Supreme Court. So Southern states seceded from the union, launching what Ross and other historians have termed a "pre-emptive counter-revolution." Looking at demographic trends today, Ross sees some white voters are making a similar calculation.

"What you have is the kind of pre-emptive anger of a certain part of the white population that understands within the next decade or two, Anglo-WASP America -- white Anglo-Saxon America -- is going to be a minority in this country," Ross said. "And they're angry about that. And so Trump is the leader, he's the Jefferson Davis of his own time."

Listen to the interview with Ross in the latest episode of the HuffPost politics podcast "So, That Happened," embedded below. The discussion starts at the 24-minute mark.

To Ross, a parallel with the mid-19th century American South is clearer than the common refrain that Trump is a fascist, although he emphasizes that Trump shares key characteristics with fascist leaders of the 20th century -- a propensity for political violence, aggressively xenophobic hypernationalism and a loathing of the political left.

"Donald Trump is certainly on the road to fascism," Ross said. "He is right now doing things that fascists do."

Ross says Trump would cross the line when people start wearing specific colors to identify with him. Mussolini's blackshirts, Adolf Hitler's brownshirts and William Dudley Pelley's silver shirts were all militant enforcers of their movement's tough-guy nationalist cause.